Since you fix them, save them, and lose them upon reopening, it
sounds like you are not opening and saving an Excel file as one of the
repliers mentioned. File should be .xls use File, save or
if it is not .xls then file, save as.

If you want to allow a mixture of 5 digit and 9 digit US zip codes,
you would be best formatting the column as text before entry.
Also as text you can use zip codes from any country, and more
important for those US only zip codes -- you can sort them.

After formatting as text which would only help with new entries
you can fix your existing entries with a macro. see
Fix up for 5 digit US zip codes (#fixUSzip5)
http://www.mvps.org/dmcritchie/excel/join.htm#fixUSzip5
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HTH,
David McRitchie, Microsoft MVP - Excel [site changed Nov. 2001]
My Excel Pages: http://www.mvps.org/dmcritchie/excel/excel.htm
Search Page: http://www.mvps.org/dmcritchie/excel/search.htm

"Ofelia" wrote in message ...
I have a zip code that begins with a zero. I try to format the cell and it
appears to work, but it does not show the zero in the formula bar. Then I'll
save it but when I reopen the worksheet it does not save it. Is there some
other way of doing this? Please Help!- Thanks